Don, obviously, the RDBMS is persistent storage, AKA, it is one
example of, "someplace that won't vanish when your web server
restarts".
I notice that Paul Graham, and most others who talk about the beauty
of using continuations or closures for web programming, never
mention what happens when their big Lisp (or whatever) server-side web
application restarts, which makes me suspect that they're just keeping
them in memory, no persistence at all. Which obviously is Not Good
Enough much of the time. ("Why is my shopping cart empty all of a
sudden?")
